Device for measuring distance and method for operating said type of device

ABSTRACT

The invention relates to a device ( 10, 10′ ) for contactless distance measurement, especially a hand-held device which allows a distance (d) between a target object ( 18 ) and at least one reference point ( 20 ) of the device ( 10 ) to be determined by means of an emitted measuring signal ( 16 ), especially by means of a modulated measuring signal. Said device comprises at least one housing ( 12, 13, 56 ) with a first end ( 34 ) facing the object ( 18 ) to be measured and a second end ( 35 ) facing away from the object ( 18 ) to be measured, and an output unit ( 22, 28, 29, 31 ) for representing the results of measurement. The invention is characterized in that at least one subsection of the distance between the object ( 18 ) to be measured and the end ( 35 ) of the housing ( 12, 13, 56 ) facing away from the object can be associated with a plurality of measured distance values via a length meter scale ( 36, 38, 54 ) that can be represented by means of an output unit ( 22, 28, 29, 31 ). The invention also relates to a method for operating said device, especially a method for operating a digital measuring stick, the measuring stick ( 10, 10 ′) of finite length having an optical output unit ( 22, 28 ) for representing a length meter scale ( 36, 38 ) and the zero point of the length meter scale ( 36, 38 ) being outside the measured range represented by the output unit ( 22, 28 ) and being determined via a distance measurement, especially an electro-optical distance measurement.

The present invention relates to a device for measuring distance, inparticular for contactless distance measurement, with which a distancebetween a target object and at least one reference point of the devicemay be determined, using an emitted measurement signal. The presentinvention also relates to the operation of a device of this type, inparticular a method for operating a digital meter rule.

RELATED ART

In the determination of distances, a distinction in made between adirect measurement by making a direct comparison of a distance with ameasurement means, e.g., a ruler, a tape-measure, or a folding rule, andby performing an indirect measurement using contactless, e.g.,electro-optical distance-measuring devices. Electro-opticaldistance-measuring devices make it possible to determine distances usingtransit time or phase measurements of a measurement signal.

The indirect distance-measuring devices on the market are designednearly exclusively as measuring devices for determining a distancevalue, and not as auxiliary devices for use to perform actionsassociated with measurement, e.g., determining and marking points orlines.

Publication EP 15 666 58 A1 makes known a hand-held device for measuringdistances that emits transmission beams via optics located in a housingtoward the background region of an object to be measured, and thencollects the reflected beams. This device also includes a component thatis connected with the housing, which may be extended beyond the housingin order to measure short distances in the direction of propagation ofthe transmission beams. One embodiment of this device provides acomponent that serves as a spacer and extends beyond the housing by afixedly predetermined length. The fixedly predetermined length of thisspacer is at least as great as the critical distance in front of thehousing of the measuring device within which it is not possible to carryout optical measurements on surface areas.

DISCLOSURE OF THE INVENTION

The inventive device for measuring distance, with which a distancebetween a target object and at least one reference point of the devicemay be determined in a contactless manner, using an emitted measurementsignal, in particular a modulated measurement signal, includes a housingwith a first end that faces the object to be measured, and a second end,which faces away from the object to be measured. The device alsoincludes an output unit for depicting measured results. Advantageously,at least one subsection of the distance between the object to bemeasured and the opposite end of the housing is displayable using alength-measurement scale via the output unit of the device. This meansthat a length-measurement scale and, therefore, distance values, inparticular a large number of distance values, may be assigned to atleast one subsection of the distance between the object to be measuredand the opposite end of the housing of the device via the output unit.

The inventive device therefore makes it possible to determine a singlequantitative distance value and to display it—as is possible, e.g., withdevices according to the related art—and to depict an entirelength-measurement scale that displays a finite range of the distance tobe measured, and/or the distance between the object to be measured andthe end of the measuring device that faces away from the object.

In this manner, the inventive device serves as a meter rule, inparticular a digital meter rule, with a measurement scale, in particulara length-measurement scale, which is displayable in the output unit ofthe device, in particular graphically, and which may display thedistance values across an entire subsection of the section that wasmeasured.

A user of the inventive device is therefore advantageously informed of aspecific distance value between the device and an object to be measured,and he has—as with a device for measuring distances directly—ameasurement scale that depicts the particular distance to the object tobe measured, across a range having a finite length.

When operating a device of this type, the function of which correspondsto that of a digital meter rule, the zero point of the measurement scaleof the meter rule, which is located outside of the measurement rangedepicted in the output unit of the device, is determined via acontactless distance measurement, in particular, e.g., via anelectro-optical distance measurement. With a method of this type, it isadvantageously possible, using a meter rule of finite length, e.g.,typically from 0.3 to 1 meter, to measure significantly greaterdistances, i.e., several meters in length, while simultaneouslydisplaying an entire range of distances and relative distances, as isthe case, e.g., with a classical folding rule for a limited measuringrange.

Advantageous refinements of the inventive device and/or the inventivemethod for operating a device of this type are possible due to thefeatures listed in the dependent claims.

In particular, the length-measurement scale, which is reproduced usingthe output unit, may be depicted in a variable manner such that itchanges as this measurement distance between the device and a targetobject increases and/or decreases in accordance with the distancemeasured between the device and the object to be measured.

The measurement scale of the inventive device advantageously includesscale divisions and/or numerical values. It is particularly advantageouswhen the measurement scale includes numerical values, which representthe particular distance between the associated scale division and themeasurement object, so that the measurement scale becomes alength-measurement scale. When the distance between the device and ameasurement object varies, the scale divisions and/or the numericalvalues assigned to the scale divisions are varied accordingly, and theyare communicated to a user in their updated form via the output unit ofthe device.

This scale adjustment may take place, e.g., automatically, as soon asthe device operates in a fixed measurement mode and measures thedistance continually.

This is made possible, e.g., by the fact that a computer unit integratedin the device determines the distance between a reference point of thedevice and the object to be measured and, based on this distance,generates a length-measurement scale across at least one subsection ofthe longitudinal extension of the measuring device, which may bedisplayed via the output unit of the measuring device.

The housing of the inventive device advantageously includes a lay edge,which is essentially parallel to the direction of the measurement signalused for contactless distance measurement. This lay edge advantageouslyforms a ruler, which may be used to draw lines and paths, in particularfor drawing straight lines from the lay edge onto a surface. To draw thelines, the inventive device and/or a lay edge of the device that servesas a ruler is placed on certain points of the drawing surface, then thelay edge of the edge is traced, e.g., with a pencil. The shape of theedge is thereby transferred to the background as a line.

Advantageously, with the inventive device, the output unit fordisplaying the measurement scale is located essentially parallel, i.e.,within the framework of production-related tolerances, to a lay edge ofthe housing. This makes it possible to directly transfer measurementpoints that may be read off using the measurement scale to a background,e.g., a wall, a ceiling, or the floor of a housing or a building. Giventhat the inventive device displays not just one measured value, butrather graphically depicts an entire measurement range with intermediatescale values, it is possible to transfer several dimensions and/ordistances and, in particular, relative distances, based on just onedevice position, without the need to change the position of thedistance-measuring device. In particular, a lay edge that is parallel toa measurement signal direction makes it possible to also transfer longerand, in particular, straight lines or paths to the background. Thehousing of the device—with its parallel sides—therefore advantageouslyserves as a ruler. Since the inventive device determines not only asingle distance value, but rather an entire range of distance values,which may be in the magnitude, e.g., of 30 cm, it is not required, inparticular, to position the measuring device exactly in the direction ofthe measurement signal.

In contrast to devices of the related art, with which, e.g., in thefixed measurement mode of the distance-measuring device, the device mustbe moved into a desired distance position using a very steady hand and agreat deal of time, in order to mark off a measure or to draw a marking,the inventive measuring device saves handling time, since the relativedistance in the direction of the measurement signal of the device may befixed exactly across a relatively large measurement range using themeasurement scale that is displayed. It need only be ensured that theend point of the path that was measured falls within the range that isdepictable on the display.

In contrast to classical rulers, which have been known for a long timefor use to measure distances directly, the inventive device provides ameasurement range that is not limited to the length of the ruler. Withthe inventive device, the measurement range is limited by themeasurement range of the contactless distance measurement. Thismeasurement range that is accessible via contactless distancemeasurement may range from a few centimeters to more than 100 meters.

Advantageously, the orientation of the measurement scale that isdepictable via the output unit of the measuring device may be switchedrelative to the housing. For example, the display of numerical valuesmay be rotated by 180° depending on the orientation of the inventivedevice. This ensures that the measurement scale of the inventivemeasuring device is much easier to see, and enhances itsuser-friendliness. To realize this, a position sensor or tilt sensor maybe integrated in the inventive device.

The housing of the inventive device advantageously includes anadditional scale, e.g., a fixed scale with marks, which is formed, inparticular, in the region of the lay edge of the housing. A second scaleof this type that is formed on the housing makes it possible to easilytransfer and mark off measurement points and paths on a background. Thevariable, electronic measurement scale, which may be displayed in theoutput unit, advantageously corresponds with the fixed mechanical scaleon the housing of the device.

In an advantageous embodiment of the inventive device, the measurementsignal that is used for contactless distance measurement is anelectromagnetic measurement signal, e.g., a light signal or a radarsignal. In a particularly advantageous manner, a modulated laser signalis suitable for use here, with which a contactless distance measurementmay be carried out in a known manner, e.g., using a transit timemeasurement or a phase measurement of the signal.

In alternative embodiments of the inventive device, an acoustic signal,e.g., an ultrasonic signal, may also be used for contactless distancemeasurement.

The inventive device for contactless distance measurement combines theadvantages of indirect and direct length measurement. Distances that maybe measured and/or marked off only by using a ruler or a conventionalmeter rule—in a laborious manner, if at all—may now be easilyascertained and characterized. For example, paths that are severalmeters long may also be determined as a “one-man operation”, due to thecompact design of the inventive device. The process of transferring ameasure from the measuring device, e.g., to a background is simplifiedand greatly accelerated, since the device need not be positioned at anexact point in the direction of the distance to be measured.

Further advantages of the inventive device and/or of an inventive methodfor operating a device of this type result from the description, below,of an exemplary embodiment.

DRAWING

Exemplary embodiments of an inventive device are depicted in the drawingand are described in greater detail in the description below. Thefigures in the drawing, their descriptions, and the claims containnumerous features in combination. One skilled in the art will alsoconsider the features individually and combine them to form furtherreasonable combinations. In particular, features of different exemplaryembodiments may be combined to form further reasonable combinations.

FIG. 1 shows an inventive device for contactless distance measurement,in a schematic overview depiction,

FIG. 2 shows an exemplary embodiment of an inventive device,

FIG. 3 shows an alternative exemplary embodiment of an inventive device,in a perspective overview illustration,

FIG. 4 shows a detailed view of an output unit of the inventive deviceaccording to an embodiment shown in FIG. 2 or FIG. 3,

FIG. 5 shows a schematic illustration of an alternative output unit foran inventive device,

FIG. 6 shows the use of the inventive device for measuring very shortdistances.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

FIG. 1 shows a schematic overview of an inventive device for distancemeasurement. Device 10 includes a housing 12, inside of which electroniccomponents for signal generation, signal detection, and signalevaluation are located. These electronic components are labelled as agroup and symbolically with reference numeral 14 in the schematicdepiction in FIG. 1. In addition to these electronic elements, theinterior of the housing may include optical elements—depending on theembodiment—such as collimation lenses or objectives. Mechanicalelements, e.g., mechanical connections, may also be located insidehousing 12. The device also includes all known components of adistance-measuring device, in particular an electro-opticaldistance-measuring device. For orienting the device in a specificmanner, the device includes a tilt sensor 15, which is depictedsymbolically as a mechanical vial in FIG. 1. It may also be anelectronic tilt sensor or the like.

The inventive device emits a measurement signal 16 in measurement signaldirection 17, measurement signal 16 being reflected or scattered on atarget object 18, so that a portion of the emitted, returningmeasurement signal 16 reaches housing 12 of device 10 once more and maybe sensed using a not-shown detector of electronic components 14. Thedistance d between target object 18 and measuring device 10, inparticular the distance between target object 18 and a reference pointor a reference plane 20 of the device, may be detected in a known mannervia a transit time measurement of measurement signal 16, or via a phasemeasurement, which evaluates, e.g., the relative phase shift between themeasurement signal traveling to target object 18 and the measurementsignal that was reflected on the target object and is returning to themeasuring device.

A measuring device of this type may be realized, e.g., as a laserdistance-measuring device, an ultrasonic measuring device, or a radardistance-measuring device by integrating appropriate sensors andreceivers and the associated signal control and evaluation in housing 12of measuring device 10. Within the framework of the description of theinventive device, reference is made to publications DE 102 32 878 A1 andDE 198 11 550 A1 for a more detailed explanation of the mode ofoperation of a device of this type for measuring distance. Thosepublications describe a basic possible mode of operation of adistance-measuring device of this type, which is designed as a laserdistance-measuring device. Reference is therefore simply made theretowith regard for signal generation and evaluation.

The inventive device for measuring distance also includes an output unit22, in particular an optical output unit 28, with which the results of adistance measurement may be displayed. Using output unit 22 it is alsopossible to depict a measured value that was determined using tiltsensor 15.

Housing 12 of device 10 includes a lay edge 24, which extendsessentially—i.e., within the framework of the productiontolerances—parallel to output unit 22.

The output unit itself, which is designed as an optical output unit, maybe designed as an electro-optical display and has an extension inmeasurement signal direction 17 that is much greater than its extensionin the direction orthogonal thereto. In preferred embodiments, theextension of output unit 22 in measurement signal direction 17 is manytimes greater than the extension in the direction perpendicular thereto.The extension may be, e.g., 10 to 30 cm, while the extension in thedirection orthogonal thereto may be only 2 to 5 cm, for instance.

FIG. 2 shows an exemplary embodiment of an inventive device. Housing 12,which is essentially rectangular and is made, e.g., of a plastic or alight metal, e.g., aluminum, includes a housing opening 26, throughwhich optical display 28 of output unit 22 is visible. Display 28 isoriented essentially parallel to the direction of measurement signal 16and parallel to lay edge 24 of housing 12 of the device. Display 28,which serves as output unit 22, extends along a considerable portion ofthe longitudinal extension of the measuring device in the direction ofmeasurement signal 16. Display 28 is located close to lay edge 24 ofhousing 12 of measuring device 10.

After the device is switched on using operating elements 30, which arenot shown explicitly in FIG. 2, a linear scale 36, for instance, withdiscrete scale divisions is depicted directly in display 28 of outputunit 22 across the entire longitudinal extension of output unit 22. Thereference point for this length-measurement scale is then, reasonably,end 35—opposite to the outlet window—of housing 12, which is the leftend of the housing shown in the view of the output unit in FIG. 2. Inthis operating mode, inventive device 10 serves as a classical ruler ormeter rule, but with an, e.g., digital, electro-optical depiction of thescale values. In a mode of this type, the inventive device may be usedlike a normal meter rule for performing direct measurements.Advantageously, it is also possible to switch between differentmeasurement systems, such as the common metric system used in Europe,and the U.S. inch system.

If, in addition, measurement signal 16, in particular an opticalmeasurement signal, is activated using a related operating element 30,the distance to housing edge 34 is no longer displayed, but, instead,the distance between measuring device 10 and a target object 18 isdisplayed. To this end, distance d between target object 18 and areference plane and/or a reference point 20 of the inventive device isdetermined, e.g., using the known phase-measurement method and, based onthe distance to reference point 20 of the device, a relatedlength-measurement scale 36 is then computer-generated in output unit22, so that it depicts the distances between the scale divisions of thismeasurement scale to the target object. In this operating mode of theinventive device, distances between the measuring device and a targetobject may be depicted across the entire range depicted in display 28.If, e.g., the distance between a target object 18 and the referencepoint and/or reference plane 20 of the measuring device are/is changed,the length-measurement scale of the measuring device is automaticallyupdated, so that it depicts the distance between individual scaledivisions and measurement object 18 exactly and in an up-to-date manner,so that at least one subsection of the distance between an object 18 tobe measured and end 35 of housing 12 facing away from the object isdisplayed using length-measurement scale 36 via output unit 22 of thedevice.

The inventive measuring device is therefore equivalent to a meter rule,in particular a digital meter rule, whose zero point of the measurementscale is located outside of the measurement scale displayed in outputunit 22. When measurement signal 16 is activated, the zero point of thismeasurement scale may also be located, in particular, clearly outside ofthe housing of the device.

In alternative embodiments, measurement signal 16 may also be activateddirectly when the measuring device is switched on, so that the measuringdevice immediately finds itself in the second, contactless measurementmode described above.

The device may operate, e.g., in a fixed measurement mode, in which thecurrent distance between the device and the particular target object orreference point is measured in an uninterrupted manner or with a specialclock rate, and is depicted in the display.

In an alternative manner, a further measurement mode of the inventivedevice may provide only a single measurement, which is initiated, e.g.,when an operating element is actuated. In accordance with the distanceto the target object that is measured, the depiction of the scale on theoutput unit is shown, e.g., in a single image.

With the inventive measuring device, it is also possible, e.g., torecord a single measured value in a single measurement, and to store itin the device using a “memory function”. This stored or “tapped” valuemay now be transferred easily to another background using the inventivedevice. In the “memory mode”, the output unit indicates, e.g., usingarrows, in which direction the device should be slid so that thedistance that is currently being measured corresponds to the distancethat was previously recorded. If the end point of the distance to bemarked off is located within the range of the measurement scale, thisend point is displayed in the corresponding point in the output unit, sothat a user may mark off the measure that was previously determined. Inthis manner it is possible to transfer a measurement that was recordedor “tapped” once to a large number of backgrounds. For instance, a largenumber of boards may be marked off with the same measurement, so thatthey may then be cut. As an alternative, it is also possible to notmeasure or “tap” the measured value to be marked off, but rather tofirst enter it directly in the measuring device via a keypad withdigits, and to store it there. In the “memory mode”, the output unit ofthe device indicates, e.g., using arrows that point to the left orright, in which direction the device should be slid so that the distancethat is currently being measured corresponds to the distance value thatwas previously recorded.

FIG. 3 shows an alternative embodiment 10′ of an inventive measuringdevice. The device includes a housing 13 with a measurement head 42, inwhich, e.g., a laser distance-measuring device or an ultrasonicdistance-measuring device is located. The measurement signal passesthrough an outlet window 43 located on end 34 of the device facing theobject and exits housing 13, and is reflected on a target object whichis not shown in FIG. 3. A portion of the measurement signal returns tothe housing via inlet window 45. An evaluation and computer unit 44 ofthe device is located on end 35 of the device that is opposite tomeasurement head 42 and therefore faces away from the object, whichdetermines the distance between the device and the target object, e.g.,via a transit time measurement or a phase evaluation. Related operatingelements and input buttons, for example, may also be provided in theregion of evaluation unit 44, which are depicted symbolically as asingle operating element 46 in the illustration shown in FIG. 3. Outputunit 22—in the form of an electro-optical display 29—is located betweenmeasurement head 42 and computer unit 44. The device includes a fixedscale 48 on both longitudinal sides of electro-optical display 29, fixedscale 48 being installed on housing 13 of the device. These scales areused to transfer measured values to a background. In alternativeembodiments of the inventive device, the measurement head and theevaluation and computer unit may also be integrated in a housing, andthey may be located, in particular, on only one side of the display.

This mode of operation of the device and, in particular, the mode ofoperation of the output unit correspond to those described above, andthey will be described in greater detail below with reference to theexemplary embodiments shown in FIGS. 2 and 3.

FIG. 4 shows a detailed view of housing 12 and 13 of inventive device 10and 10′ according to FIG. 2 and FIG. 3, respectively, in the region ofoptical display 28 and 29, respectively. The display is a digitaldisplay with a variable scale that is composed of scale marks andassigned numerical values. The numerical values change as the distancebetween the measuring device and a target object increases or decreases.It is also possible, in principle, to use, e.g., LEDs or laser displays.Scale divisions 36 of 1 cm are shown in exemplary display 28 and 29.This scale is subdivided further into 5 mm-increments by additionalscale divisions 38. A further subdivision, e.g., into 1 mm-increments,is also possible, and may be displayed in the output unit, e.g., if soprompted by the user. An embodiment of the inventive device may also beadvantageous with which the scale may be divided into more or fewerincrements, depending on the absolute distance from a target object thatis measured. For example, the measurement uncertainty of the inventivedevice may be adapted to the absolute distance between the device andthe target object, as was proposed by the applicant in DE 102 32 878 A1for distance-measuring devices. In accordance with the measurementuncertainty applied, it is therefore possible to display the measurementscale with different resolutions.

Numerical values are assigned to scale divisions 36, which represent thedistance from each scale division 36 to a target object 18. Theinventive device therefore displays the distance between a target objectand a reference plane or a reference point of the measuring device, andit displays the absolute distances between a measurement scale and thetarget object, within a finite range. The absolute distance betweenmeasurement points and a target object, and, therefore, the relativedistance between these measurement points, may be read out across theentire range of the output unit, and they may be marked off, e.g., on abackground. To this end, housing 12 of inventive device 10 also includesa fixed scale division 40, i.e., it is fixed relative to the housing,which is located, e.g., across the entire longitudinal extension ofoutput unit 22 and/or across the entire longitudinal extension ofhousing 12, and which is fixed to housing 12. A fixed scale division ofthis type with 1 mm-increments is used in the exemplary embodiment shownin FIG. 2 and in FIG. 3. Other scale divisions are also feasible, ofcourse.

In addition to the embodiment of the electronic length-measurement scaleshown in FIG. 4, depending on the application, it is also possible todepict only a portion of the entire measurement range, or to depict onlya single measured value, thereby making it possible—as with conventionallaser distance-measuring devices—to also perform individualmeasurements, e.g., relative to a reference point or a reference edge ofthe device (e.g., the front or rear end of the measuring device). Inparticular, it is provided that the reference point—on the device—forthe distance measurement may be switched.

FIG. 5 shows a greatly simplified version of an exemplary embodiment ofan output unit of this type. A single measured value 50 (320.5 cm inthis case) is advantageously provided with at least one scale mark 52,with which—via its relation to fixed measurement scale 54 on devicehousing 56—the measured value itself or relative lengths may be markedoff, based on measured value 50, which was measured in a contactlessmanner. To this end, fixed measurement scale 54 of housing 56 isadvantageously designed as a relative scale, and measured value 50,which was determined in a contactless manner, is displayed in a fixedposition in output unit 31. To orient the device, a mechanical vial 58is integrated in housing 56, on end 34 of the device that faces theobject. As an alternative, an electronic tilt sensor may also beintegrated in the device shown in FIG. 5 or in the other, previouslydescribed devices. The position and placement of the vials or theinclinometer may vary, depending on the embodiment.

A user may select the different measurement modes using relatedoperating elements, based on the task at hand. The measurement modes maybe selected, e.g., using a keypad, or a rotating wheel on the housing.

It is possible, e.g., in a special measurement mode of each of theembodiments of the inventive device described above, to store a measuredvalue using a “memory button”, or to enter a desired distance valuedirectly in the measuring device using a button sequence. When thisstored value is marked off, e.g., on a different background, thenumerical value may be emphasized separately in the display. This maytake place, e.g., in a display of the output unit as shown in FIG. 5.When the desired value is marked off, e.g., an arrow or a line isdisplayed, which indicates the position of the measured value to bemarked off based on the position of the output unit relative to thetarget object. The user of the inventive device is therefore informedabout which direction he should slide the device in order for it to belocated the desired distance away from a certain target object. When themeasured value to be marked off appears in the display of the device,i.e., when the end point of the distance to be marked off is locatedwithin the range of the length-measurement scale displayed in the outputunit, the arrow or line is hidden and the measured value is displayed atthe point that represents its distance from the reference point. In thismanner, a user is easily informed about which direction he should movethe inventive device relative to the target object in order to comewithin the range of the desired distance.

It is advantageous in particular to also provide the inventive devicewith a mechanical or electronic vial that makes it possible to also usethe inventive device as an inclinometer, and to ensure that the deviceis level when a distance measurement is carried out using the device.

In addition, by integrating a position sensor in the housing of theinventive device, the output unit may be designed such that the distancevalues that are displayed are always displayed in a position that iseasiest to read. For example, depending on the orientation of thehousing, the numerical value, which is assigned to a scale division, maybe rotated, e.g., by 90° or 180° relative to the orientation shown inFIG. 3, to ensure that a user is able to easily read the scale. Thedigital scale of the output unit therefore provides the user with goodorientation across the entire measurement range and, in particular,across the display range of the device.

In contrast to conventional electro-optical distance-measuring devices,it is also advantageously possible to measure and/or mark off valuesstarting at a distance of 0 mm from the device. FIG. 6 shows ameasurement situation of this type.

By locating the measurement components, i.e., in particular thetransmitter and receiver for the measurement signal, in the housing ofthe device, it is possible to avoid the “dead zone” in the close rangeof object distances, which is a few centimeters and which is common withdistance-measuring devices, e.g., laser distance-measuring devices. Thisis possible, in particular, with the inventive device given thatmeasurement components 14 are set back in “linear housing” 12 of thedevice by at least a distance D, which is equal to the length of thedead zone. With the inventive device, it is therefore possible to evenperform measurements relative to target objects that are located at adistance of zero or only a few centimeters away from the end—near theobject—of the housing of the device. Positioning the device relative tothe target object, which may also require that the device and targetobject be in contact with each other, is also considered to be acontactless distance measurement within the scope of the inventivedisclosure, however, since the determination of the particular distancebetween the measuring device and the target object takes place in acontactless manner using measurement signal 16.

The inventive device is not limited to the designs presented in theexemplary embodiments.

In particular, the inventive method is not limited to the use of lightsignals, in particular laser signals, as the measurement signal. It isalso possible, e.g., to use radar signals or electromagnetic signals ingeneral as the measurement signal to determine a distance between atarget object and the device and/or a reference point of the device.

As an alternative, it is also possible to use acoustic measurementsignals, in particular ultrasonic signals, for these distancemeasurements.

In addition to the use of modulated measurement signals, with whichdistance may be measured based on the signal transit time and/or thephase displacement of the measurement signal, which travels back andforth, it is also basically possible to use triangulation methods todetermine the distance between the target object and the measuringdevice.

The output unit is not limited to the use of an electro-optical display.It is possible, e.g., to depict the measurement scale purelymechanically by displaying a rotating strip on which the measureddistance values are shown.

The inventive device is therefore equivalent to a meter rule, inparticular a digital meter rule, which combines the advantages of directand indirect length measurement. In particular, the advantageous housingdesign, which has an increased longitudinal extension of the housing inthe direction of the measurement that is considerably greater than theextension of the housing in both directions orthogonal thereto, makes itpossible to perform measurement-related actions, e.g., determining andmarking off points, distances between points, or lines. The longitudinaldisplay—which is digital—designed in this manner makes it possible todepict a variable scale composed of scale marks and numerical values,which may change, in particular, as the measurement distance increasesor decreases, and which are adapted to the related distance values. Inparticular, it is now possible for a single user to determine andcharacterize distances that previously required a great deal of effortto measure or mark off using a ruler or a conventional, finite meterrule. When lines are marked off, the functionality of the inventivedevice therefore advantageously corresponds to that of a conventionalruler.

1. A device (10, 10′) for contactless distance measurement, inparticular a hand-held device, with which a distance (d) between atarget object (18) and at least one reference point (20) of the device(10) may be determined using an emitted measurement signal (16), inparticular a modulated measurement signal, and including, at least, ahousing (12, 13, 56) with a first end (34), which faces the object (18)to be measured, and a second end (35), which faces away from the object(18) to be measured, and including an output unit (22, 28, 29, 31) fordepicting measured results, wherein several measured distance values areto be assigned to at least one subsection of the path between the object(18) to be measured and the opposite end (35) of the housing (12, 13,56) via a length-measurement scale (36, 38, 54) that is displayable inthe output unit (22, 28, 29, 31).
 2. The device as recited in claim 1,wherein, using the output unit (22, 28), it is possible to display avariable measurement scale (36, 38), which changes as the measurementdistance increases or decreases, in accordance with the distancemeasured between the target object (18) and a reference point (20) ofthe device.
 3. The device as recited in claim 1, wherein the housing(12, 13, 56) of the device includes a lay edge (24), which isessentially parallel with the measurement-signal direction (17).
 4. Thedevice as recited in claim 3, wherein the output unit (22, 28) fordisplaying the measurement scale (36, 38) is essentially parallel withthe lay edge (24) of the housing (12).
 5. The device as recited in claim1, wherein the measurement scale (36, 38) is composed of scale divisionsand/or numerical values.
 6. The device as recited in claim 1, whereinthe measurement scale (22, 28, 31) includes numerical values, whichrepresent the distance from a related scale division to the measurementobject (18).
 7. The device as recited in claim 1, wherein theorientation of the measurement scale (22, 28, 31) relative to thehousing (12, 13, 56) may be switched.
 8. The device as recited in claim1, wherein the device (10, 10′) is provided with at least one tiltsensor, in particular at least one mechanical or electronic vial (15,58), which enables the device (10, 10′) to be used as an inclinometer.9. The device as recited in claim 1, wherein the housing (12, 13, 56)includes at least one additional scale (26, 54), in particular a fixedscale with marks, which is formed in particular in the region of a layedge (24) of the housing (12, 13).
 10. The device as recited in claim 1,wherein the output unit (22) is an electro-optical display (28, 29, 31)with which the length-measurement scale (22, 28, 31) may be displayed indigital form.
 11. The device as recited in claim 1, wherein thedimensions of the output unit (22) in the direction (17) of themeasurement signal (16) are multifold greater than they are in thedirection orthogonal thereto.
 12. The device as recited in claim 1,wherein the measurement signal (16) is an electromagnetic measurementsignal, in particular a modulated electromagnetic measurement signal.13. The device as recited in claim 12, wherein, the measurement signal(16) is an optical measurement signal (16), in particular a lasersignal.
 14. The device as recited in claim 1, wherein the measurementsignal (16) is an acoustic signal, in particular an ultrasonic signal.15. The device as recited in claim 1, wherein the receiving andtransmitting unit (14) of the device is set back from the first end (34)of the housing (12, 13, 56) by a distance D such that objects that areplaced against the first end (34) of the device may also be measured.16. A method for operating a digital meter rule (10, 10′), with whichthe meter rule (10, 10′) of finite length includes an optical outputunit (22, 28, 29) for depicting a length-measurement scale (36, 38),wherein the zero point of the length-measurement scale (36, 38) islocated outside of the measurement range displayed in the output unit(22, 28) and is determined via a distance measurement, in particular anelectro-optical distance measurement.
 17. The method as recited in claim16, wherein the measurement scale (22, 28) of the meter rule changes asthe distance (d) between the meter rule (10) and a measurement object(18) changes, in accordance with the particular distance.
 18. The methodas recited in claim 16, wherein the output unit (22, 28) depicts ameasurement scale (36, 38) with numerical values, each of whichrepresents the distance between the scale division (36) associated withthe numerical value and the measurement object (18).